what is &$ used for in php code example

Example 1: php pass by reference

<?php
function appendToString(&$string)
{
    $string .= 'Cool Im appended';
}

$str = 'I am a start and - ';
appendToString($str);
echo $str;    // outputs 'I am a start and - Cool Im appended'
?>

Example 2: what does $ sign mean in php

<?php

$name = "World";
echo "Hello, $name";

# $ i.e. "sigil" is used to distinguish a string variable from rest of the string.